The sample "The music just turns me on!" featured in That's Enough from Jet Set Radio is from the Mikey Dread song "Saturday Night Style.
(appears at 4:47)
That's Enough also has an odd laughing sample that plays throughout the song. This is from the acapella version of the Peech Boy's song "Don't Make Me Wait."
(Appears at 2:32)
This laugh also appears in the song Metal Scratchin from Sonic Rush
Speaking of that song, Metal Scratchin's vocal sample "Go ahead, scratch me!" is from the Looney Tunes Merry Melody "Scratch Me."
I Like it Like That from Jet Set Radio Future's "You make me feel so good!" is from the Mikey Dread song "Comic Strip".
The sample "I Like it, I Like it!" is from a Speedy Gonzales cartoon, Cattails for Two.
(Appears at 3:17; This is sped up [most likely to avoid any copyright issues] you can find the episode unaltered online)